The present invention generally relates to a guide device particularly adapted for use in connection with a manually manipulatable abrading device of the endless belt variety in order to prevent gouging of the surface of a workpiece when a raised imperfection in such workpiece is abraded to lie essentially flush with such surface. More particularly, the present invention relates to an improvement in a guide of the type disclosed in commonly assigned U.S. Pat. No. 4,178,723.
The guide device disclosed in U.S. Pat. No. 4,178,723 is characterized as comprising one or more circumferentially expandable guide wheels, which are mounted coaxially with a contact wheel over which an abrasive belt passes while in contact with a workpiece. Specifically, each guide wheel includes a continuous guide ring or tire formed of a resiliently deformable material and means to support and adjustably effect changes in the radius of the guide ring, as required to compensate for variations in thickness of the abrasive belt either due to wear or the utilization of belts of differing thickness.
It has been found that in certain grinding operations, as for instance where a user exerts substantial bearing pressure on the abrasive belt in a non-uniform manner, that slight gouging of the surface of a workpiece occurs incident to non-uniform compression of the resiliently deformable tires, as the grinder is moved along a weld. Attempts to avoid this problem by the simple expedient of reducing the degree of resiliency of the guide ring or tire to a point where gouging of the workpiece surface will not occur as a result in expected fluctuations in bearing pressure, have not met with success, since the guide wheel or tire then loses resiliency to a point where same can not be readily adjusted.